1. Technical Field
The present invention relates to a head driving mechanism that drives a plurality of printing heads, and a printing apparatus including the head driving mechanism.
2. Related Art
JP-A-2011-67964 (in particular, see FIG. 1) discloses a printing apparatus that dispenses a liquid such as ink or recording fluid from a plurality of printing heads onto a recording medium such as a film, to thereby record color images. In this apparatus, the recording medium is wound, with a predetermined tension applied thereto, around a circular column-shaped platen drum the recording medium, and supported on the curved surface of the platen drum. The plurality of printing heads are provided around the circumferential surface of the platen drum.
To record high-quality images, it is essential that a paper gap, in other words a distance between a nozzle tip (outlet of the ink) of the printing head and the recording medium is maintained at a proper value, and hence the printing heads have to be moved according to the thickness of the recording medium, to thereby locate the printing heads at a proper distance from the platen drum with high accuracy. However, no specific reference is made in JP-A-2011-67964 about such a positioning method.
According to JP-A-2011-67964, in addition, the printing heads are radially arranged with respect to the rotation axis of the platen drum, so that, with respect to the landing position of the ink, the printing heads of the respective colors are oriented perpendicular to the curved surface of the platen drum. Accordingly, on the assumption that one of the printing heads is set to move in a first direction, another printing head has to be moved in a second direction which is inclined with respect to the first direction, and thus the printing heads have to be moved in different directions. Therefore, many of the printing apparatuses of such a type include head driving mechanisms provided for the respective printing heads, for moving the printing heads in a direction perpendicular to the curved surface of the platen drum.
However, providing the same number of head driving mechanisms as that of the printing heads not only constitutes a major factor that increases the size and cost of the printing apparatus, but also makes it difficult to locate the printing heads at the correct position with high accuracy, because of individual variation among the head driving mechanisms.